Let love in

It seems inevitable that my past becomes so intertwined with my present. It is forever a part of me but in some ways I wish I could let pieces of it go. I mature and constantly I am changing, although, without fail, some things just come back to haunt me. I have made it clear to myself I can be alone, I can be independent and I realize I don't NEED someone else to live a happy life. Another person around just makes days somewhat better, more exciting. Sharing life, growing together, learning together, changing together. I desperately want to let someone in, give them all of me and in turn have all of them. Lock their love up tight and never allow them to hurt because of me. Yet, something is constantly stopping me, filling my head with doubt, endlessly spilling questions through my mind. Can I trust? Will I be hurt? Will love be unconditional? I can't let my past relationships affect my current. It's is tiresome and something I constantly wish I could stop worrying about. Being hurt scars you, leaves a mark you won't forget so how do I get past it? How do I ensure I won't let it hurt my future relationships?